1. Field of the Invention
The present invention relates to an ink containing pigment, an ink cartridge containing the ink, and an ink jet recording method. The ink can be suitable for a yellow ink jet ink.
2. Description of the Related Art
In recent years, recorded images have been used indoors and outdoors as notices, such as posters and point-of-purchase (POP) advertising. The light resistance and the scratch resistance of images should therefore be improved in ink jet recording. Inks containing pigment, that is, pigment inks are increasingly used to improve these characteristics. However, pigment inks generally have lower color developability than inks containing dye. Furthermore, pigment inks generally produce images of low-glossiness because of pigment particles. Thus, pigment inks need to achieve high glossiness and color developability, as well as high light resistance and scratch resistance.
Among inks used in ink jet recording, yellow inks are particularly required to produce images having high color developability. Thus, various yellow pigment inks have been proposed.
For example, C.I. pigment yellow 74 having high color developability, C.I. pigment yellow 128 having high light resistance, and a combination thereof have been intensively studied. For example, Japanese Patent No. 03455764 discloses a combination of C.I. pigment yellow 74 and C.I. pigment yellow 128 that can achieve both high color developability and high light resistance of images. Japanese Patent Laid-Open No. 2000-345080 discloses a recording method in which high-concentration regions and low-concentration regions are recorded with an ink containing C.I. pigment yellow 74 and an ink containing C.I. pigment yellow 128, respectively, to achieve both high color developability and high light resistance of images. Japanese Patent Laid-Open No. 2004-099734 discloses that an ink containing C.I. pigment yellow 74, 110, and 128 in which the proportion of C.I. pigment yellow 74 ranges from 10% to 20% of all the pigments can achieve both high light resistance and high color developability of images. Japanese Patent Laid-Open No. 2007-099917 discloses that an ink containing C.I. pigment yellow 74 and 138 in combination with a specific polymer can improve the color developability, glossiness, and light resistance of images and has high storage stability and ejection stability.
Although Japanese Patent No. 03455764 and Japanese Patent Laid-Open Nos. 2000-345080 and 2004-099734 can achieve high color developability and light resistance of images by utilizing the characteristics of the pigment, no attention is given to polymers, and the images have insufficient glossiness. Although paying attention to the characteristics of a polymer, Japanese Patent Laid-Open No. 2007-099917 aims to improve the color developability and glossiness of images and the storage stability of recorded images recognized as yellowing and employs only a single polymer with respect to the relationship between the pigment and the polymer, as in the patent literatures described above. All these patent literatures pay no attention to scratch resistance. The scratch resistance of images recorded with known ink jet inks, including the inks described in these patent literatures, is so low that the images are often damaged by a scratch with fingernails.